The embodiments disclosed herein generally relate to implantable devices and more particularly to systems and methods for improving performance of implantable devices.
The performance and accuracy of transcutaneous and implantable sensors is believed to be affected by biofouling, tissue reactions at or near the site of the sensor, and reduction of analyte access due to inflammation, blood vessel regression and fibrous encapsulation. In addition to causing problems with sensor function, tissue reactions and sensitivities due to the presence of transcutaneous and totally implantable sensors can cause discomfort to a user, and can lead to inflammation and infection.
In diabetic patients, determination and effective management of blood glucose levels is critical to minimizing diabetes related complications. Traditionally finger sticking and external monitors coupled with insulin injections have been used to manage blood glucose levels in patients with diabetes, but because of the need for frequent “finger sticks”, many patients with diabetes do not adequately monitor their blood glucose levels. More recently, the development of implantable glucose sensors to continuously monitor blood glucose levels (CGM) and continuous insulin infusion (subcutaneous insulin infusion, SCII) have significantly enhanced the management of blood glucose levels in patients with diabetes. Current glucose sensors used in CGM limits the need for frequent blood analysis and provides significantly enhanced insights into the dynamic nature of blood glucose changes in patients with diabetes. Unfortunately current commercial sensors have a limited functional lifespan in vivo (3-7 days).
When CGM and SCII are combined in a single patient, but under the supervision of the patient, it is referred to as an “open loop” system. When the implanted glucose sensor (i.e. CGM) controls insulin infusion (i.e. SCII) without the intervention of the patient this is referred to as a “closed loop” system or artificial pancreas. Development of an artificial pancreas (i.e. closed-loop technology) to clinically manage diabetes is a major goal of the diabetes community. Recently, there have been an increasing number of success stories of short-term closed-loop clinical trials.
Central to the goal of the development of long-term closed loop technology is the development of a long-term glucose sensor with high accuracy that can effectively control insulin infusion (SCII). Because of questions of in vivo reliability and limited lifespan of current commercial sensors effectiveness in both open and closed loop systems is limited. Much of the lack of sensor performance in vivo is thought to be the result of sensor induced inflammation, fibrosis and fibrosis-induced vessel regression at the site of sensor implantation. It has often been argued that the loss of blood vessels proximal to the sensor (i.e. fibrosis induced vessel regression) at the sensor implantation site is a major cause of the loss of effective CGM in open and closed loop systems.
Two of the major problems associated with the uses of prosthetic meshes are 1) their propensity to induce chronic inflammation and excessive fibrosis, with resulting loss of mesh pliability and mechanical integrity, increased stiffness at the site of the implantation, and 2) post mesh implantation infections. Frequently the result of poor mesh biocompatibility is excessive inflammation and subsequent fibrosis. This can result in limited tissue mobility of the groin_and abdominal wall and chronic pain and loss of mobility for the patient. It is generally accepted that foreign body reactions (FBRs) characterized by chronic inflammation, giant cell formation, fibrosis (collagen plates) and vessel regression_result in loss of mesh function via mesh contraction and mesh distortion (e.g. loss_of functional pore size), as well as mesh calcification. Clearly, improving the biocompatibility of the mesh implants (i.e. decreasing inflammation and fibrosis)_and mesh biostability, given the susceptibility of PET to enzymatic & hydrolytic degradation is anticipated to result in improved mesh function by decreasing mesh distortion, calcification and loss of mechanical integrity that are all too commonly associated with mesh-based reconstructive surgeries.
In addition to biocompatibility, infection associated with mesh implantation frequently compromises mesh function and dramatically impacts a patient's daily life. The timeframe for mesh related infections range from 10 days post implantation (short term) up to several years post mesh implantation (long term infections). Mesh infections increase pain and discomfort, hospital stay, healing/recovery time, cost, morbidity, mortality, and may require additional surgery to remove device.
It would be useful to develop products, systems and methods that maintain acceptable performance over longer periods of time, and that reduce tissue reactions and sensitivities at or near the implantation site.